Structural Analysis of Proteins from Bacterial Secretion Systems and Their Assemblies by NMR Spectroscopy.

Bacterial secretion systems are built up from proteins with different physicochemical characteristics, such as highly hydrophobic transmembrane polypeptides, and soluble periplasmic or intracellular domains. A single complex can be composed of more than ten proteins with distinct features, spreading through different cellular compartments. The membrane and multicompartment nature of the proteins, and their large molecular weight make their study challenging.

Comprehensive Fragment Screening of the SARS-CoV-2 Proteome Explores Novel Chemical Space for Drug Development.

SARS-CoV-2 (SCoV2) and its variants of concern pose serious challenges to the public health. The variants increased challenges to vaccines, thus necessitating for development of new intervention strategies including anti-virals. Within the international Covid19-NMR consortium, we have identified binders targeting the RNA genome of SCoV2.

Insights into the specificity for the interaction of the promiscuous SARS-CoV-2 nucleocapsid protein N-terminal domain with deoxyribonucleic acids.

The SARS-CoV-2 nucleocapsid protein (N) is a multifunctional promiscuous nucleic acid-binding protein, which plays a major role in nucleocapsid assembly and discontinuous RNA transcription, facilitating the template switch of transcriptional regulatory sequences (TRS). Here, we dissect the structural features of the N protein N-terminal domain (N-NTD) and N-NTD plus the SR-rich motif (N-NTD-SR) upon binding to single and double-stranded TRS DNA, as well as their activities for dsTRS melting and TRS-induced liquid-liquid phase separation (LLPS). Our study gives insights on the specificity for N-NTD(-SR) interaction with TRS.

Large-Scale Recombinant Production of the SARS-CoV-2 Proteome for High-Throughput and Structural Biology Applications.

The highly infectious disease COVID-19 caused by the SARS-CoV-2 poses a severe threat to humanity and demands the redirection of scientific efforts and criteria to organized research projects. The international consortium seeks to provide such new approaches by gathering scientific expertise worldwide. In particular, making available viral proteins and RNAs will pave the way to understanding the SARS-CoV-2 molecular components in detail.

Structure and Assembly of the Enterohemorrhagic Escherichia coli Type 4 Pilus.

Bacterial type 4a pili are dynamic surface filaments that promote bacterial adherence, motility, and macromolecular transport. Their genes are highly conserved among enterobacteria and their expression in enterohemorrhagic Escherichia coli (EHEC) promotes adhesion to intestinal epithelia and pro-inflammatory signaling. To define the molecular basis of EHEC pilus assembly, we determined the structure of the periplasmic domain of its major subunit PpdD (PpdDp), a prototype of an enterobacterial pilin subfamily containing two disulfide bonds.

Allantoin reduces cell death induced by cisplatin: possible implications for tumor lysis syndrome management.

Massive lysis of tumor mass in cancer patients under chemotherapy regimens generates high levels of uric acid, leading to what is known as tumor lysis syndrome (TLS). Rasburicase, a recombinant urate oxidase, converts urate to allantoin, which is readily excreted by the kidneys. Even though there is a high production of allantoin from urate in cancer patients following rasburicase treatment, there are no studies on how allantoin excess could interfere with chemotherapy.

Structural basis of the signalling through a bacterial membrane receptor HasR deciphered by an integrative approach.

Bacteria use diverse signalling pathways to adapt gene expression to external stimuli. In Gram-negative bacteria, the binding of scarce nutrients to membrane transporters triggers a signalling process that up-regulates the expression of genes of various functions, from uptake of nutrient to production of virulence factors. Although proteins involved in this process have been identified, signal transduction through this family of transporters is not well understood.

Interaction of a partially disordered antisigma factor with its partner, the signaling domain of the TonB-dependent transporter HasR.

Bacteria use diverse signaling pathways to control gene expression in response to external stimuli. In Gram-negative bacteria, the binding of a nutrient is sensed by an outer membrane transporter. This signal is then transmitted to an antisigma factor and subsequently to the cytoplasm where an ECF sigma factor induces expression of genes related to the acquisition of this nutrient.

The structure of HasB reveals a new class of TonB protein fold.

TonB is a key protein in active transport of essential nutrients like vitamin B12 and metal sources through the outer membrane transporters of Gram-negative bacteria. This inner membrane protein spans the periplasm, contacts the outer membrane receptor by its periplasmic domain and transduces energy from the cytoplasmic membrane pmf to the receptor allowing nutrient internalization. Whereas generally a single TonB protein allows the acquisition of several nutrients through their cognate receptor, in some species one particular TonB is dedicated to a specific system.

(1)H, (13)C and (15)N resonance assignments of the periplasmic signalling domain of HasR, a TonB-dependent outer membrane heme transporter.

TonB-dependent transporters (TBDTs) are bacterial outer membrane proteins that internalize nutrients such as vitamin B12, metal complexes, heme, some carbohydrates, etc. In addition to their transport activity, several TBDTs are also involved in a signalling cascade from the cell surface into the cytoplasm, via their periplasmic signalling domain. Here we report the backbone and side chain resonance assignments of the signalling domain of HasR, a TonB-dependent outer membrane heme transporter from Serratia marcescens as a first step towards its structural study.